This invention relates generally to a device for indicating rotation of a seed metering shaft used with a grain drill. This indicator provides a visual indication of shaft rotation whereby a farmer can easily check proper functioning of the seed metering shaft while pulling the seed drill through the field.
As is well known, grain drills are pulled behind tractors to plant seeds which are dropped from a grain hopper into a furrow formed by the grain drill. The flow of seed from a grain hopper is regulated by a rotating seed metering shaft as the grain drill moves across the field. In the past, there have been problems determining whether the planter is functioning properly. This results because of the dusty conditions which exist behind a tractor when pulling a grain drill. Under these conditions, it is difficult for an operator to detect when the seed metering shaft fails to rotate. As a consequence, an operator often continues to move over long distances unaware that the seed metering shaft has stopped rotating and that seeds are not being planted. Since the grain drill, as part of its normal operation, is also covering the furrows after the seed is planted, there is seldom any visible indication available to the operator that anything is wrong. Thus, the operator may continue moving over a field thinking he is planting seed when in fact he is not.
Seed sensors have been devised to sense seed flowing along a path from the seed hopper to the ground. For example, U.S. Pat. No. 4,164,669 to Knepler illustrates such a seed sensor installed on a seed planter. These seed sensors sense movement of the seed to indicate whether the planter is operating properly.
Another type of indicating device is shown in U.S. Pat. No. 3,921,159 to Steffen. This patent illustrates a device for monitoring the shaft rotation of a seed metering shaft. This device employs a magnet attached to the seed metering shaft and corresponding electronic circuitry which senses the magnet as it rotates with the shaft. When the shaft stops rotating, a visual indication is provided that a problem has occurred and that the planter is not functioning properly.
The applicant is also aware of a device for monitoring rotation of a seed metering shaft which includes a striker rod secured to the seed metering shaft transversely thereto. An indicator arm has one end mounted to be struck by the striker rod as the seed metering shaft rotates and has a second end which moves corresponding to the first end. As the seed metering shaft turns, the striker rod installed on the shaft strikes the indicator arm. Movement at the second end of the indicator arm provides a visual indication of shaft rotation.
Numerous problems were encountered with this striker rod device. The indicator arm motion was confusing in that the indication was generally steady for most of a shaft revolution cycle, but then an abrupt, jerky movement was displayed as the striker rod struck the indicator arm. With this device, an operator would have to watch the indicator for at least one complete revolution of the seed metering shaft. In addition, the striker rod mounted to the shaft tended to bend after use and the device became inoperable.
There has been a need for a simple mechanical indicator to indicate continued movement of the seed metering shaft which indicator continuously provides an indication of seed metering shaft movement.